Once upon a time 'git -C "" cmd' errored out with "Cannot change to
'': No such file or directory", therefore the completion script took
extra steps to run 'git -C "." cmd' instead; see fca416a41e
(completion: use "git -C $there" instead of (cd $there && git ...),
2014-10-09).
Those extra steps are not needed since 6a536e2076 (git: treat "git -C
'<path>'" as a no-op when <path> is empty, 2015-03-06), so remove
them.
While at it, also simplify how the trailing '/' is appended to the
variable holding the prefix path components.
Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
6bf0ced4e2